Some analysts say it will become a destination store. Others warn that the company faces an uphill battle to gain a foothold in an already overcrowded domestic supermarket sector.

Either way, Whole Foods -- founded 30 years ago by Texan John Mackey, a Birkenstock-wearing, chicken-keeping advocate of natural foods -- is jumping, rather than wading, in.

The company's new store in the affluent neighborhood of Kensington will stretch across three floors of a former art deco department store, making it far bigger than any existing grocery store in Britain. It plans to follow that up with another 30 to 40 stores across the country.

Like Whole Foods stores across the United States, the focus is on fresh, organic, natural food. There will be no artificial flavors, colors, sweeteners, preservatives or hydrogenated fats and customers will be paid around 10 cents for each bag they supply themselves.

There's also more than just food. Along with offering facials and chair massages, the company will sell clothing, towels and linens made from organic cotton.

In the United States, it is a celebrity-spotters' haunt, with Angelina Jolie, Reese Witherspoon and Jake Gyllenhaal all seen stocking up in its glistening wide aisles.

Whole Foods itself describes its stores as an "exciting place to shop, eat, meet friends, and enjoy naturally delicious food" in a festive street market atmosphere.

"What they offer is breadth and depth of range," said Bryan Roberts, an analyst at Planet Retail. "People will travel into London to visit this store."

But others are not so sure.

"It's a leap of faith, even though the market is theoretically favorable," said Robert Clark, an analyst at the Retail Knowledge Bank consulting group.

Britain's supermarket sector is much more competitive than in European countries like France, where retailers are not allowed to sell at below-cost prices, and the United States, whose vast size means that many market players -- and the resulting competition -- are largely regional.

As retailers generally divide along the lines of those selling cheap goods and those offering upmarket products, Whole Foods is positioning itself at the top end of the British market, hoping to grab a big slice of a market worth around $26 billion.

But Clark said Whole Foods prices are likely to be above even those currently at the crest of the domestic market, like the current upmarket leader Waitrose, and may be beyond the reach of too many customers.

Known colloquially in some quarters of the United States as "Whole Paycheck," the store could be even more expensive on this side of the Atlantic because of higher British real estate and labor costs, Clark said.

Clark adds that many other stores have already turned to organic foods to win more customers and market share. Tesco PLC, J Sainsbury PLC and Marks & Spencer PLC all have organic, natural food lines that are more expensive than their standard lines, but still likely cheaper than the Whole Foods product.

In anticipation of Whole Foods' arrival, the trio have also started offering organic grow-your-own vegetable boxes. Tesco even cheekily trademarked "Tesco Wholefoods" for its range.

Whole Foods' plan to open more stores across the country may also be hampered by Britain's restrictive town planning system and astronomical property prices.

"The only concern ... is securing space for new stores," said Roberts. "They do need to operate from fairly large sites."

However, Roberts suggested that a regulatory investigation already under way into the stranglehold of the country's big four supermarkets in the sector could result in a more welcoming environment for Whole Foods.

The company has already helped transform food retailing in the United States despite its relatively small size as larger competitors launched new products to compete.

Mackey has helped create Whole Foods' cult status by declining to draw a salary, donating his stock options to the company's charities and setting up a fund for staff with emergencies.

However, after almost a decade of rapid growth to just under 200 stores, there are some concerns in the U.S. about stagnating profits as the company incurs the high cost of building new stores. Additionally, its acquisition of smaller rival Wild Oats Markets Inc. is still being held up by a regulatory review.

A London policeman walks past the Whole Foods Market in London's Kensington High Street, west London Friday June 1, 2007. Whole Foods Market Inc., America's most successful organic supermarket chain, opens its massive flagship London store next week. Some analysts say it will become a must-travel-to destination store. Others warn that the company faces an uphill battle to gain a foothold in an already overcrowded domestic supermarket sector. (AP Photo/Alastair Grant)